An important thing to safely drive a vehicle is to comprehend positions of various objects (such as an obstacle and a pedestrian) existing around a vehicle. A recent-day vehicle captures a surrounding image by using a plurality of in-vehicle cameras, and thereby detects the position of an object or allows a driver to easily comprehend the position of an object existing around the vehicle.
For example, there is proposed a technology that applies bird's-eye view conversion to an image captured by an in-vehicle camera into an image (bird's-eye image) captured as if from a direction to look down at the vehicle, displays the image, and thereby allows a driver to easily comprehend positional relation between the vehicle and an object.
The technology assumes that the in-vehicle camera is installed on the vehicle at a correct installation position and at a correct installation angle. However, an installation error always occurs when the in-vehicle camera is installed. There is a need to eliminate an influence of the installation error by detecting installation positions and installation angles on all in-vehicle cameras at factory shipment of vehicles. The contents of a process on a captured image are optimized to eliminate an influence of the installation error on the assumption that each in-vehicle camera is installed on a vehicle at the installation position and the installation angle of the in-vehicle camera.
The installation position and/or the installation angle of the in-vehicle camera is detected or the amount of misalignment from the correct installation position and installation angle is detected to optimize the contents of a process on a captured image. This may be referred to as calibration of the in-vehicle camera.
The installation position or the installation angle of the in-vehicle camera may vary from the factory shipment condition, due to some reasons such as a vibration during vehicle travel or interference of the in-vehicle camera with something. In such a case, it is inconvenient to transport the vehicle to a maintenance factory and calibrate the in-vehicle camera. To solve this, there is proposed a technology (Patent Literature 1), in which capture regions for adjacent in-vehicle cameras partially overlap. If the installation position or installation angle of an in-vehicle camera changes from the factory shipment condition, the technology then calibrates the in-vehicle camera whose installation position or installation angle has changed, based on a captured image from an overlap region for the adjacent in-vehicle camera.